Avoid sillyness if not a valid IPv6 address

1 files changed, 22 insertions, 10 deletions

diff --git a/ipv6rs.c b/ipv6rs.c
index 0ca5b179..f48d01c7 100644
--- a/ipv6rs.c
+++ b/ipv6rs.c
@@ -378,7 +378,7 @@ add_router(struct ra *router)
 void
 ipv6rs_handledata(_unused void *arg)
 {
-	ssize_t len, l, n, olen;
+	ssize_t len, l, m, n, olen;
 	struct cmsghdr *cm;
 	int hoplimit;
 	struct in6_pktinfo pkt;
@@ -632,22 +632,34 @@ ipv6rs_handledata(_unused void *arg)
 			for (n = ndo->nd_opt_len - 1; n > 1; n -= 2,
 			    op += sizeof(addr.s6_addr))
 			{
-				l += ipv6_printaddr(NULL, 0, op, ifp->name) + 1;
+				m = ipv6_printaddr(NULL, 0, op, ifp->name);
+				if (m != -1)
+					l += m + 1;
 			}
 			op = (uint8_t *)ndo;
 			op += offsetof(struct nd_opt_rdnss,
 			    nd_opt_rdnss_lifetime);
 			op += sizeof(rdnss->nd_opt_rdnss_lifetime);
 			tmp = opt = malloc(l);
-			for (n = ndo->nd_opt_len - 1; n > 1; n -= 2,
-			    op += sizeof(addr.s6_addr))
-			{
-				tmp += ipv6_printaddr(tmp, l, op, ifp->name);
-				*tmp++ = ' ';
-				if (lifetime > 0)
-					has_dns = 1;
+			if (opt) {
+				for (n = ndo->nd_opt_len - 1; n > 1; n -= 2,
+				    op += sizeof(addr.s6_addr))
+				{
+					m = ipv6_printaddr(tmp, l, op,
+					    ifp->name);
+					if (m != -1) {
+						l -= (m + 1);
+						tmp += m;
+						*tmp++ = ' ';
+						if (lifetime > 0)
+							has_dns = 1;
+					}
+				}
+				if (tmp != opt)
+					(*--tmp) = '\0';
+				else
+					*opt = '\0';
 			}
-			(*--tmp) = '\0';
 			break;
 			
 		case ND_OPT_DNSSL: